Lancaster Newspapers is reporting that an electrical problem in the area of an extension cord likely caused a Lancaster city house fire Monday that killed two people and injured three firefighters trying to rescue them, an official said.

"We've located some extension cords we think are the most probable cause of the fire," Trooper Dustin Shireman, a state police fire marshal, said on Friday. "There was nothing suspicious to suggest the fire was incendiary. It was accidental."

The blaze started in the basement of the middle row home at 225 E. Madison St., he said. The ignition source is undetermined.